1. Field of the Invention
The present invention relates to a multiple-output power device which outputs a plurality of regulated voltages, and also relates to a mobile device using the power device thereof.
2. Description of the Related Art
In the technical field of the mobile devices, supplying voltages to a plurality of functional circuit elements has been individually performed by controlling their respective voltages. In such a related art, a plurality of regulators for outputting the plurality of voltages are embedded in a semiconductor integrated circuit body (hereinafter called an IC chip body), whereby the IC chip body is packaged as a semiconductor device which is used for a multiple-output power device.
FIG. 4 is a view showing the configuration of a multiple-output power device 400 as a related art. In FIG. 4, an IC chip body 300 is provided with a first regulator 301 for outputting a first output voltage Vo1; a second regulator 302 for outputting a second output voltage Vo2; and an nth regulator 30n for outputting an nth output voltage Von.
A source voltage Vcc supplied to a power supply pin 312 is input to these regulators 301 to 30n. At this time, the source voltage Vcc is supplied commonly to the regulators by way of a bonding wire 313, a power source pad 314, and internal wiring 311. In other words, input sides of the regulators 301 to 30n are connected commonly to the bonding wire 313 and the internal wiring 311.
The regulators 301 to 30n, being constituted by series regulators, for instance, are controlled so as to generate predetermined output voltages Vo1 to Von on the basis of a reference voltage. The output voltages Vo1 to Von are supplied to respective load devices by way of corresponding output pads 321 to 32n, bonding wires 331 to 33n, and output pins 341 to 34n. 
In FIG. 4, the source voltage Vcc is taken as a voltage to be input to the regulators 301 to 30n However, there is a case where the source voltage Vcc is boosted by a booster circuit and the thus-boosted voltage is supplied as an input voltage to the regulators 301 to 30n as disclosed in JP-A-8-234851.
As mentioned previously, as to the multiple-output power device 400 in the related art, the power supply pin 312, the bonding wire 313, the power supply pad 314, and the internal wiring 311 are shared among the plurality of regulators 301 to 30n. Accordingly, when one of the regulators 301 to 30n has become activated/deactivated, or when the state of the load device that is connected to that regulator has changed, said situations might cause a voltage drop by the resistance of the bonding wire 313 or the resistance of the internal wiring 311, those provided in a stage preceding the regulator. The influence of the voltage drop also changes the input voltages of the other regulators. Particularly, in the mobile device which operates on battery power, the respective regulators 301 to 30n are activated/deactivated very frequently from a necessity of saving power consumption. Consequently, activation/deactivation by some of the regulators 301 to 30n often affects another regulators, which ends up deteriorating the voltage control properties of the entire multiple-output power device.
Although it depends on a regulator, there is another problem such that the length of the power supply line within the IC chip body 300 becomes excessively long because of restrictions placed on the internal wiring 311 being used as a common connection, which increases resistance of the wiring so as to deteriorate properties of the regulator, such as deviations in an input/output voltage difference or the like.
More specifically, for instance, the voltages Vo1 to Von output from the respective regulators 301 to 30n are controlled to predetermined voltages in accordance with specifications of the respective load devices. As mentioned previously, the voltage input to the respective regulators is the common source voltage Vcc. Therefore, in such a circuit configuration, the voltage differences between the common input source voltage Vcc and the respective output voltages Vo1 to Von are likely to cause internal loss energies in the respective regulators 301 to 30n. Especially, there has been pointed out a problem of the internal energy loss becoming relatively large one in a low voltage output regulator.